1. Field of the Invention
The present invention relates to generally to fingerprint scanning and imaging. More specifically, the present invention relates to a system and method for capturing a fingerprint image.
2. Related Art
Biometrics are a group of technologies that provide a high level of security. Fingerprint capture and recognition is an important biometric technology. Law enforcement, banking, voting, and other industries increasingly rely upon fingerprints as a biometric to recognize or verify identity. See, Biometrics Explained, v. 2.0, G. Roethenbaugh, International Computer Society Assn. Carlisle, Pa. 1998, pages 1-34 (incorporated herein by reference in its entirety).
Fingerprint scanners having cameras are available that capture an image of a fingerprint. A signal representative of the captured image is then sent over a data communication interface to a host computer for further processing. For example, the host can perform one-to-one or one-to-many fingerprint matching.
In order to capture a fingerprint image electronically, a light source is typically directed towards a fingerprint capture surface that reflects light from the light source towards a camera. The fingerprint capture surface is generally glass. Contact between the surface of a finger and the fingerprint capture surface causes the reflected light to be representative of the fingerprint of the particular finger placed against the fingerprint capture surface. This reflection then must be captured by camera. The intensity of the reflected light varies greatly in such a system. For example, variations due to manufacturing tolerances and techniques used to produce the light source can affect the intensity of light directed towards the fingerprint capture surface. Such a variation can, however, be determined at the time of manufacture and can be factored into the design of the system. Other variations cannot be determined in advance, and so must be compensated for in the field.
For example, the quality of contact between a finger and the fingerprint capture surface plays a large role in the intensity of the reflected light. A very dry skin surface on a clean fingerprint capture surface may result in a low intensity level of reflected light. On the other hand, an oily skin surface and/or a less-clean fingerprint capture surface may result in a high level of reflected light.
As a result of the above variations, a fingerprint scanner system and method that captures an acceptable fingerprint image is needed. Moreover, in order to produce an effective and simple to use fingerprint scanner, it is desired that such a system and method for capturing an acceptable fingerprint image be implemented with little needed user input.